Schedule is all fuxked up.

So, my 2 month old had been on a pretty good sleeping schedule. He was doing AWESOME. He would go to sleep sometime between 12-3 and he would sleep until 9-11. Then last night he stayed up all night until 6 this morning before he finally went out. Currently right now hes sleeping, should I try to keep him up or just let him sleep? How did you Mommy's fix it when your little ones schedules got messed up?